A superconducting acceleration system is an apparatus that imparts kinetic energy to charged particles and is provided with a hollow superconducting acceleration cavity. A superconducting acceleration cavity has a shape in which large-diameter portions and small-diameter portions are alternately repeated in the longitudinal direction and is formed by welding together blanks made of pure niobium after subjecting them to press molding and cutting processing.
In Patent Literatures 1 and 2, a plurality of half cells 11 that have a large diameter at one end and a small diameter at the other end are connected together in the longitudinal direction to form a cavity main unit 1. In Patent Literature 3, dumbbell cells having a dumbbell shape in which the periphery of the center portion thereof is depressed and bowl-shaped half cells are combined and connected in the longitudinal direction to form a superconducting cavity 1.